KIRO-TV reported that the Seattle Fire Department estimates the fire caused $1.5 million in damages. One firefighter was treated for a knee injury he suffered fighting the fire.

The fire was under control quickly, authorities said. It ignited at 10 p.m. Thursday, about a half-hour before the fireworks show at Gas Works Park.

Cory Crosby, who works for the marina, told KIRO-TV he saw the fire and moved some boats to try to prevent it from spreading farther.

The owner of the boat yard told The Seattle Times that the “heroic effort” of company employees at the scene prevented the fire from damaging more boats.

Alan Bohling, CEO of Seattle Boat Co., which operates the Lake Union Skylaunch Marina., said the first boat that burned was nearest to the street where “errant fireworks” from a nearby hillside likely ignited it.

The marina, which opened in 2007, serves 250 boat customers, Bohling said.

Witnesses said many people were shooting off fireworks in the area, but the cause is still being investigated.